1. Field of the Invention
The present invention relates to a developing device and an image forming apparatus.
2. Description of the Related Art
Generally, an image forming apparatus, such as a laser printer, an LED printer, a digital copier, or a general paper facsimile, transfers and prints an image signal according to an input digital signal on a printing medium, that is, a paper, in a visible image form.
The image forming apparatus includes a developing device, a laser-scanning device, and a fixing device.
The developing device includes an image carrier, such as a photosensitive drum, developing a visible image, and a developing member transferring a developer, such as toner, to the image carrier.
An electrostatic latent image is formed at the surface of the image carrier corresponding to the visible image by light emitted from the laser-scanning device.
As an example of the developing member, a developing roller according to a contactless developing method rotates with a developing gap against the image carrier. The developing roller transfers a developer, such as toner, to the electrostatic latent image area according to the contactless developing method. The developer attached to the developing roller is attracted to the electrostatic latent image area via the developing gap by a static electricity according to a difference of electric potential between the electrostatic latent image and the developing roller. The toner attracted to the electrostatic latent image is transferred to a printing medium passing through the image carrier and the developing roller. The printing medium passes the fixing device, and the visible image transferred to the printing medium is adhered to the printing medium by a high temperature and pressure.
As the image carrier and the developing roller rotate in a forward direction, which is a direction of rotating in mesh with each other, a regular airflow is generated in the developing gap. An airflow also is generated between the printing medium and the developing device by the movement of the printing medium.
The toner particles moved from the developing roller to the electrostatic latent image via the developing gap is disturbed by the airflow, and the insufficiently-charged toner particles may not be attracted to the electrostatic latent image due to the effect of the airflow rather than adhering due to static electricity.
Additionally, toner particles may be scattered into the image forming apparatus by the airflow, thereby contaminating the inside of the device.
Accordingly, a need exists for an image forming apparatus having an improved developing device that substantially prevents developer from scattering.